Despite years of research, the cause of Alzheimer's disease remains essentially unknown. Topographic memory impairments are arguably the earliest cognitive deficits observed in Alzheimer's disease, and the brain areas involved in topographic memory are the first to show degenerative changes. Previous research has shown a link between impairment of topographic memory in humans with bilateral vestibular loss. However, no one has heretofore attempted to correlate topographic memory loss with impairment of the vestibular system in individual members of a normal elderly population at risk for Alzheimer's disease. This Phase I project will develop biobehavioral markers for topographic memory impairments and their possible antecedents. These topographic and possible vestibular biobehavioral markers will be integrated into a web-based interface and decision-support system that will provide an early warning indicator for those at risk of topographic memory failure and possibly Alzheimer's disease. Ultimately, this system may be used not only to identify those at risks for Alzheimer's disease, but also those who may be amenable to vestibular remediation. The development of the biobehavioral markers has the potential to have a profound impact on public health and achieve significant commercial success. This Phase I study has two Specific Aims: Specific Aim 1. Create Software to Evaluate Topographic Memory and/or Vestibular Impairment Specific Aim 2. Evaluate the Correlation between Topographic Memory and Vestibular Function in a Human Clinical Trial PUBLIC HEALTH RELEVANCE: An estimated 5.4 million Americans have Alzheimer's disease in 2012. Payments for care associated with Alzheimer's disease are estimated to be $200 billion annually. Despite years of research, the cause of Alzheimer's disease remains largely unknown. The development of biobehavioral markers that could indicate early onset of Alzheimer's disease and perhaps provide targets for disease prevention or treatment would have a significant impact on public health.